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49 Cards in this Set
- Front
- Back
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What are the three main functions of the kidneys?
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1. Excretion
2. Homeostasis 3. Endocrine |
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What are the three main substances that the kidneys excrete?
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1. Urea
2. Creatinine 3. Metabolites of hormones and exogenous chemicals |
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What are the five endocrine pathways in which kidneys participate?
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1. Renin (secreted by JG cells) - controls ECF volume and helps to regulate BP
2. Erythropoietin 3. Activation of vitamin D (cholecalciferol) 4. Biosynthesis of prostaglandin PGE2 5. Cyclic nucleotide biosynthesis (cAMP and cGMP) |
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What is the organization of the kidney?
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1. Lobe = medullary poyramid + associated cortical region
2. Each lobe associated with minor calyx 3. Calyces feed into the ureter |
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What portions of the nephron are found in the cortex?
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All renal corpuscles and convoluted portions of the nephron
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What portions of the nephron are found in the medulla?
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1. Nephral loops of Henle
2. Collecting ducts |
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What is present in the medullary rays? In what part of the kidney is it found?
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1. Some of the loops of Henle
2. All of the collecting tubules 3. Found in the cortex at the center of one lobule |
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What structure is at the lobule boundaries?
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Interlobular arteries
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What are the arteries/veins supplying the kidney?
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1. Renal artery and vein
2. Interlobar aa and vv 3. Arcuate aa and vv 4. Interlobular aa and vv |
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Where are the interlobar arteries and veins found?
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Enter renal columns alongside the renal pyramids
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Where are the arcuate arteries and veins found?
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Arch across in between the cortex and medulla
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Where are the interlobular arteries and veins found? What is their function?
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1. Supply/drain blood for glomeruli of two lobules, can branch
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What is the arteriolar structure at the glomerulus?
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1. Afferent arterioles
2. Glomerulus 3. Efferent arterioles |
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What is the peritubular capillary plexus?
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Capillaries from efferent arterioles that wrap around convoluted tubules of the cortex
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What are the vasa recta?
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Capillaries from efferent arterioles that surround nephral loops in the medulla
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Define uriniferous tubule.
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Nephron + collecting duct
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What are the components of a renal corpuscle?
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1. Bowman's capsule
2. Glomerulus 3. Mesangial cells |
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What are the two layers that make up Bowman's capsule and what is the cellular organization of these layers?
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1. Parietal layer: simple squamous epithelium
2. Visceral layer: highly modified simple squamous epithelium |
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How is the parietal layer of Bowman's capsule organized?
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1. Contiguous with proximal tubule epithelium at urinary pole
2. Contiguous with visceral epithelium at vascular pole 3. Encloses the urinary (capsular) space and forces all ultrafiltrate to enter the PCT |
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What is the function of the visceral layer?
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Contains podocytes that invest the glomerular capillaries
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How do pedicels relate to podocytes?
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1. Cells with small, finger-like processes called pedicels that partially invest the glomerular capillary where they interdigitate with the pedicels of another secondary process
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Define glomerular slit diaphragm. What is its major component? What is its function?
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1. 6 nm thick, non-membranous structure between the pedicels of podocytes
2. Major component: nephrin, extracellular protein secreted by podocytes 3. Function: do not let particles larger than 10 nm to get through and be filtered |
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What is the function of podocalyxin? Where is it found?
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1. Sialoprotein (negatively charged) that ensures negatively-charged proteins greater than 69 kD are not allowed to be filtered
2. Covers the podocyte membrane |
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What is the glomerulus composed of? How is it separated from the renal corpuscle?
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1. Loops of capillaries with highly fenestrated endothelium
2. Separated from the visceral layer of the renal corpuscle by a thick basement membrane that is strongly ionic and impedes flow of proteins |
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Where are mesangial cells found? What shape are they? What is their function?
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1. Found within and outside the glomerulus between capillary loops
2. Spindle-shaped cells 3. Phagocytic and may help control GFR by contracting the glomerular capillaries |
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What is the cellular organization of the proximal convoluted tubule? How do they stain?
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1. Simple cuboidal epithelium with a brush border of densely packed, PAS stain-positive microvilli
2. Stains darker than DCT |
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What are the functions of the proximal convoluted tubule?
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1. Resorbs 60% of NaCl and urea and 65% of water, as well as proteins
2. Secretes endogenous metabolic products as well as exogenous substances such as drugs |
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What is the function of the proximal straight tubule? How does it stain?
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1. Less involved in NaCl and water resorption but rate of secretion of organic acids is 3X greater than in the PCT
2. Stains darker than PCT and also retains PAS |
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What is the cellular organization of the thin descending limb of the nephral loop? To what compounds is it permeable and impermeable?
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1. Simple squamous epithelium with no microvilli or tight junctions
2. Permeable to water but completely impermeable to salt |
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What is the cellular organization of the thin ascending limb of the nephral loop? To what compounds is it permeable and impermeable?
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1. Simple squamous epithelium
2. Impermeable to water and actively pumps sodium out into the filtrate |
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What is the cellular organization of the distal straight tubule? To what compounds is it permeable and impermeable? How does it stain?
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1. Simple cuboidal epithelium with few microvilli
2. Impermeable to water, actively pumps sodium out into filtrate 3. Stains lighter than proximal straight tubule |
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What is the cellular organization of the distal convoluted tubule? To what compounds is it permeable and impermeable? What is the result of this?
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1. Simple cuboidal epithelium
2. Impermeable to water, permeable to salts 3. Filtrate becomes hyposmotic due to water impermeability |
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Where is the macula densa found?
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In the distal convoluted tubule
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How do nephrons attach to the collecting duct system?
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By attaching to connecting segments of the CD system
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How does the epithelial cellular organization change in the collecting duct?
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1. SImple cuboidal in the connecting segment and becomes taller as you move
2. At papilla of the renal pyramid, becomes tall columnar |
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What are the two cell types found in the collecting duct? What are their functions? What junction is predominant in the cell types?
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1. Principal (clear) cells: predominate, ADH causes insertion of AQP2 proteins into the apical membrane, allows for H2O resorption
2. Intercalated (dark) cells: stains darkly, secrete H+ and resorb HCO3- 3. Predominant junction: tight junction |
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Where is the juxtaglomerular apparatus located?
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Where the distal straight tubule and beginning of the distal convoluted tubule make contact with the vascular pole of its own glomerulus
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What are the cell types found in the juxtaglomerular apparatus?
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1. JG (myoepitheloid) cells
2. Macula densa cells 3. Extraglomerular mesangial cells |
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Where are JG (myoepitheloid) cells found? What do they contain? What is their function?
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1. Afferent arteriole
2. Contains numerous membrane-bound secretion granules, myofibrils, and dense bodies 3. Secretes renin to activate the angiotensin I/II pathway, which stimulates the adrenal cortex to produce aldosterone, promoting sodium retention in the DCT |
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What is the macula densa? Where is it found? What is its function?
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1. Densely-packed epithelial cells in the wall of the first part of the DCT that contacts the vascular pole of the renal corpuscle
2. Sensitive to flow rate and NaCl concentration in its lumen 3. Releases adenosine in response to low flow rate, causing JG cells to release renin |
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Where are extraglomerular mesangial (lacis) cells found? What is their function?
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1. Fill the space in the roughly triangular area formed by the afferent and efferent arterioles and the macula densa
2. May have secretory function, but function not well known |
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What are the components of the external collecting system?
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1. Ureter
2. Urinary bladder 3. Urethra |
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What are the layers of the ureter?
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From superficial to deep:
1. Transitional epithelium 2. Lamina propria: well-innervated and vascularized loose CT 3. Tunica muscularis 4. Loose CT adventitia |
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What are the layers of the urinary bladder?
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1. Tunica mucosa
2. Lamina propria |
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What cell types are found in the tunica mucosa layer of the urinary bladder? What are their characteristics and functions?
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1. Basal cells: small and proliferative
2. Intermediate cells: make contact with BM 3. Facet cells: polyploid, large, make contact with BM, contains lenticular vesicles that allow for rapid expansion and contraction of the membrane during bladder emptying and filling |
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What are the layers associated with the lamina propria of the urinary bladder? What are their characteristics?
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1. Tela submucosa: thick layer of loose CT
2. Tunica muscularis: three interlaced layers of smooth muscle and elastic fibers; forms internal sphincter of urethra in the trigone 3. Tela subserosa: loose CT covered by peritoneum |
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What are the two layers associated with the urethra?
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1. Tunica mucosa
2. Tunica muscularis |
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How is the tunica mucosa of the urethra organized?
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1. First third: urothelium
2. Second third: intermediate patchy zone of stratified columnar epithelium 3. Last third: stratified squamous epithelium that contains urethral glands to secrete GAGs, which protect the urethral epithelium from urine |
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How is the tunica muscularis of the urethra organized?
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1. THin inner longitudinal smooth muscle layer
2. Thick outer circular smooth muscle layer 3. Intermediate portion of urethra surrounded by skeletal muscle fibers of the sphincter urethrae |
